Principles of pain management are described in Chapter 38. Adequate analgesia begins preoperatively and continues in the OR and in the PACU.

1. Opioids (IV or epidural) are the most common form of postoperative analgesia.
   1. Fentanyl, a potent synthetic opioid with a rapid onset of action, is commonly limited to the operative setting. Occasionally, however, small IV doses (25- to 50-μg IV bolus) can be titrated postoperatively to establish rapid analgesia.
   2. Morphine (2- to 4-mg IV bolus) may be repeated every 10 to 20 minutes until adequate analgesia is achieved. In children above 1 year of age, 15 to 20 μg/kg can be safely administered IV or intramuscularly at 30- to 60-minute intervals.
   3. Hydromorphone (0.2- to 0.5-mg IV bolus) may also be repeated every 10 to 20 minutes until adequate analgesia is achieved. It is a synthetic opioid approximately eight times more potent than morphine and associated with significantly less histamine release.
   4. Meperidine (25- to 50-mg IV bolus) is similarly effective. It lacks the vagotonic effect of other opiates and is frequently used to reduce post-anesthetic shivering. Meperidine must be avoided in patients taking monoamine oxidase inhibitors (serotonin syndrome) and must be administered cautiously in patients with renal insufficiency (toxic metabolite normeperidine is associated with seizures).
2. Nonsteroidal anti-inflammatory drugs (NSAIDs) and acetaminophen are effective complements to opioids. Ketorolac (15- to 30-mg IV bolus followed by 15-mg IV bolus every 6-8 hours in the perioperative period) provides potent postoperative analgesia. Other nonselective NSAIDs (ibuprofen, naproxen, and indomethacin) are also effective. Potential toxicities of all NSAIDs include decreased platelet aggregation resulting in increased bleeding risk and nephrotoxicity.
3. Adjuvant analgesics include spasmolytics (cyclobenzaprine) and small doses of benzodiazepines.
4. Regional sensory blocks can be very effective postoperatively (see Chapter 21).
5. IV patient-controlled analgesia has been shown to be superior in patient satisfaction compared with intermittent analgesia administered by the medical staff.
6. Continuous epidural analgesia should be continued postoperatively or promptly initiated in the PACU if not used in the OR.